Experimental demonstration of quantum digital signatures using phase-encoded coherent states of light

TL;DR

This paper presents an experimental quantum digital signature system using phase-encoded coherent states of light, providing information-theoretic security for message authenticity and integrity, demonstrated over optical fiber.

Contribution

The authors experimentally demonstrate a quantum digital signature scheme with security against forgery and repudiation, using phase-encoded coherent states in optical fiber.

Findings

Successful distribution of quantum signatures to two receivers

Security analysis confirms robustness against typical attack scenarios

Implementation utilizes phase encoding and polarization-maintaining fiber

Abstract

Digital signatures are frequently used in data transfer to prevent impersonation, repudiation and message tampering. Currently used classical digital signature schemes rely on public key encryption techniques, where the complexity of so-called "one-way" mathematical functions is used to provide security over sufficiently long timescales. No mathematical proofs are known for the long-term security of such techniques. Quantum digital signatures offer a means of sending a message which cannot be forged or repudiated, with security verified by information-theoretical limits and quantum mechanics. Here we demonstrate an experimental system which distributes quantum signatures from one sender to two receivers and enables message sending ensured against forging and repudiation. Additionally, we analyse the security of the system in some typical scenarios. The system is based on the interference of phase encoded coherent states of light and our implementation utilises polarisation maintaining optical fibre and photons with a wavelength of 850 nm.